Emails and Attachments
Calendars and Contacts
Shared Mailboxes

Mailboxes on Litigation Hold or In-Place Hold
OneDrive Files*
SharePoint Files within Document Libraries**
Microsoft Teams Chats (click here for more information)
Archived Mailboxes 
Shared Folders
Public Folders
Site Assets Libraries

* We only backup files and folders within OneDrive accounts

** We only backup files and folders within SharePoint Sites & Teams Sites

Altaro Office 365 Backup does not support backing up the following items (list is not exhaustive): Conversation History, Drafts, Hidden Folders, Junk Email, Notes, Outbox, Recoverable items (permanently deleted email folders), Categories, Sync Issues, Yammer, Microsoft Booking Items, Microsoft OneNote Items (files with .one extension are excluded), Audit folders (via Audit Logging), Contact groups, Items in OneDrive Recycle Bin, SharePoint customisations, SharePoint Public Sites, SharePoint Apps from SharePoint Store, SharePoint Custom Lists, malware flagged items, sensitive files flagged by the Data Loss Prevention policy and IPF.IMAP Folder Class.